1. Field of the Invention
This invention relates to a circuit for a wide bandwidth low distortion amplifier, particularly a class A transistorized amplifier capable of handling high current.
2. Description of the Prior Art
A prior art search has disclosed the following patents:
U.S. Pat. Nos. 2,761,917 and 3,239,770 employ transformer coupling as an integral part of their design. Transformers have bandpass characteristics which inherently limit the bandwidth of the amplifier, and hence limit the usefulness of the amplifier in broadband applications. The present invention is not so limited.
U.S. Pat. No. 3,594,652 does not employ transistors in a complementary relationship, whereas complementary action in the present invention has the effect of causing even order distortion products to cancel. This patent also does not use feedback loops as in the present invention.
U.S. Pat. No. 3,955,259 shows a common-emitter input, not a common-base input as in the present invention. This patent is for a common class A amplifier.
U.S. Pat. No. 2,860,193 drives its first stage common-emitter, not common-base as in the present invention, and does not provide overall feedback from the output collectors as in the present invention.
U.S. Pat. 2,955,257 is a buffer amplifier with unity gain comprising two sets of emitter followers with no feedback.
U.S. Pat. No. 3,372,344 is a unity gain buffer amplifier. It is susceptible to cross-over distortion and even-order distortion due to its asymmetry.
U.S. Pat. No. 2,959,741 is meant as a low-noise low-current front end. It does not employ complementariness.
The following patents were also cited as of general interest: U.S. Pat. Nos. 3,260,947, 3,258,704, 3,040,264, 3,204,191, 2,788,493, 3,195,064, 3,114,112, 3,500,218, and 3,628,166.